Tech in Plain Sight: Zipper Bags [Hackaday]

You probably think of them as “Ziploc” bags, but, technically, the generic term is zipper bag. Everything from electronic components to coffee beans arrive in them. But they weren’t always …read more

You probably think of them as “Ziploc” bags, but, technically, the generic term is zipper bag. Everything from electronic components to coffee beans arrive in them. But they weren’t always everywhere, and it took a while for them to find their niche.

Image from an early Madsen patent

A Dane named Borge Madsen was actually trying to create a new kind of zipper for clothes in the 1950s and had several patents on the technology. The Madsen zipper consisted of two interlocking pieces of plastic and a tab to press them together. Unfortunately, the didn’t work very well for clothing.

A Romanian immigrant named Max Ausnit bought the rights to the patent and formed Flexigrip Inc. He used the zippers on flat vinyl pencil cases and similar items. However, these still had the little plastic tab that operated like a zipper pull. While you occasionally see these in certain applications, they aren’t what you think of when you think of zipper bags.

Zipping

Ausnit’s son, Steven, figured out how to remove the tab. That made the bags more robust, a little handier to use, and it also rendered them less expensive to produce. Even so, cost was a barrier because the way they were made was to heat seal the zipper portion to the bags.

That changed in the 1960s when the Ausnits learned of a Japanese company, Seisan Nippon Sha, that had a process to integrate the bags and zippers in one step which slashed the production cost in half. Flexigrip acquired the rights in the United States and created a new company, Minigrip, to promote this type of bag.

Enter Dow

In 1964, Dow Chemical wanted to acquire the rights to the Minigrip bags to sell in supermarkets using Down’s polyethylene bags. And with this marriage, the Ziploc bag as we know it was born.

Dow continued driving down the cost, tasking R. Douglas Behr to improve how the Ziploc production line worked. Eventually, the bags were flying off the line at 150 feet per minute.

You can find plenty of videos of machines that “make” zipper bags on YouTube (like the one below). Many of them are surprisingly light on detail, and it isn’t clear now how many of them are molding zippers and how many are sealing premade zippers to bags or using rolls of bags with zippers in them already. However, the video below shows making “zip lines” from pellets and then creating bags from film. This creates giant rolls of zipper bag stock which are then cut into individual bags.

Slow Start

At first, consumers weren’t sure what to do with the zipper bags. Supposedly, a record company was set to put records in the bags but when an executive handed one to his assistant, the assistant ripped the bag open without using the zipper.

Regardless, consumers finally figured it out. Now, the zipper bag is a staple in electronics, food storage, and many other areas, too.

More Than Meets the Eye

Even the most ordinary things have details you don’t think about, but someone does. For example, zip bags can have one, two, or three zippers. Some have color indicators that show the seal. Some have strips that conceal the zipper so you can tell if the bag was opened.

There are special zippers for liquids and different ones that resist getting powder stuck in the seal. Some zip bags still have pulls, and some of those pulls are child-proof, requiring the user to pinch the tab to slide it. You can even get zipper bags that don’t use locking zippers but hook-and-loop closures.

Even though zipper bags don’t seem very glamorous, you can learn a lot from the Ausnits. Improve your product in ways that make people want to use it. Also, improve your product in ways that lower costs. We’d guess that when Ausnit bought the zipper patents, he’d never imagine how the market would grow.

You can see a talk from Steve Ausnit at Marquette University in the video below. If you’ve ever had the urge to be an entrepreneur, you can learn a lot from his talk.

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